The present invention is directed to a drawer-type circuit breaker and more particularly to a latching arrangement associated with the extendable support rails for supporting a circuit breaker body in a disconnected position and a lever arrangement associated with the movable circuit breaker for initiating the disconnecting of the circuit breaker during a drawing operation and for making the final connection during an insertion operation.
Japanese Utility Model publication No. 50-25460 published July 31, 1975 discloses a drawer-type circuit breaker wherein the circuit breaker 2 is supported for rolling movement on at least one support rail 6. A latch lever 8 is pivoted to the support rail 6 and is normally biased for engagement by a stop member 11 on the circuit breaker 2 by means of a spring 10 to prevent withdrawal of the circuit breaker from the housing. An extension rail 7 is provided with a projection 15 which allows the extension rail 7 to be supported in alignment with the support rail 6 by means of pins 12 and 13 on the support rail 6. When the extension rail is secured in place a protrusion 13a on the end of the projection engages the latch lever 8 to bias the same out of blocking position relative to the stop member 11 against the force of the spring 10 thereby allowing the circuit breaker 2 to roll outwardly from the housing onto the extension rail 7. When not in use the extension rail 7 is completely disconnected from the circuit breaker assembly and is therefore susceptible to being misplaced and therefore unavailable when needed.
The U.S. patent to Powell No. 3,663,773 granted May 16, 1972 is directed to a switch gear draw-out apparatus with a clutch interlock. A pair of support rails are pivotally mounted on the circuit breaker housing on opposite sides of the circuit breaker for movement between a vertical stored position and a horizontal operative position for supporting the circuit breaker on rollers during a drawing operation. A manually operated lever is also pivotally mounted on one side of the circuit breaker housing for controlling the movement of a cam which in turn controls the initial disconnecting movement of the circuit breaker during withdrawal and the final connection of the circuit breaker upon insertion thereof. A clutch is operatively associated with the lever and cam to prevent the operation of the cam when the circuit breaker contacts are in the closed position. In addition to requiring a complex assembly of springs and levers to operatively clutch and unclutch the lever to the cam member, a reverse movement must be applied to the lever after the initial disconnecting movement to unlatch the circuit breaker from the housing to permit the same to be drawn outwardly onto the support rails.